Relief for EN 13480 piping 1

[don1980]

Does EN 13480 (process piping standard) allow short-term pressure excursions similar to those allowed by ASME B31.3? Specifically, i'm referring paragraph 302.2.4 in ASME B31.3 which conditionally allows excursion up to 120% and 133% of design pressure, for a limited number of hours per occurrence and per year. This allows one to set a thermal relief valve at 120% of the pipe's design pressure. I'm searching to determine whether EN 13480 allows similar short-term pressure excursions, thus allowing thermal PSVs to be set at 120% of design pressure.

Thanks.

 

[don1980]

Since there haven't been any responses, I'll try clarifying the question. I was thinking that one of you from Europe could answer this. I assumed that some/many European facilities are migrating to EN 13480 as the basis for their process piping specs, rather than using ASME B31.3. However, I'm aware that adoption of harmonized standards in Europe has been slower than the EU regulators anticipated back when PED was implemented. So, perhaps EN 13480 hasn't been implemented to any significant extent - I don't know.

You're probably aware that B31.3 allows the short-term pressure excursions that I mentioned in the above post, which allows thermal PSVs to be set at 120% of the piping design pressure. My question is whether or not that's permissible for piping that's based on this new EN 13480 standard. Hopefully the answer is yes, because that allows us to maintain a uniform global practice (uniform guidance for relief designers). However, if it's not, then we'll need to stipulate that the relief designer must check which standard the piping is based on (B31.3 or EN13480) before specifying the set pressure for thermal PSVs on piping.

Thanks.

 

[don1980]

BTW, I found the answer to this question. I'll summarize what I learned in case there are others who may be interested in knowing the answer.

The EN 13480 piping standard does not have similar pressure protection guidance to that in ASME B31.3. In fact, the EN 13480 standard doesn't include any pressure protection requirements/guidance. Why? Because, unlike ASME, EU standards don't distinguish between vessels and piping when it comes to pressure protection. The same requirements apply to both. EU pressure protection standards such as ISO 4126 and EN 764-7 cover "pressure equipment" which includes piping. This was the key learning for me. I'd previously assumed that those EU standards were similar to ASME Sec VIII, in that they just covered pressure vessels. It turns out that that's not true.

ASME has separate pressure protection requirements for pressure vessels and piping. Pressure vessel requirements are in ASME Sec VIII and process piping requirements are in ASME B31.3. European standards don't make this distinction. They cover "pressure equipment", which includes vessels, piping, etc., and are not exclusively for pressure vessels. So, there's no need, or reason, for EN 13480 to say anything about pressure protection - that's already covered by other standards (e.g. ISO 4126, EN 764-7).

One of the reasons I like pressure protection work is because it never gets dull - I'm always learning something new. Although that's often a source of frustration, it also keeps it interesting.

 

[shvet]

Sorry, I have no english version of EN 13480. There is my loose translation bellow.

4.2.3.3 ...
Note - Pressure and temperature combination of loads can exceed allowable stress more than 10% if this these conditions last no more than 10% of 24-hours phase of work

Appendix ZA of EN 13480-3-2005 refers to EU 97/23/EC. EU 97/23/EC contains para. 7.3 which says the same for overpressure protection.

 

[georgeverghese]

Dont have a working knowledge of this standard, but I presume this EN 13480 guidance is why EU compliant oil/gas facilities design shows firecase RVs' on vessels and piping are all set at 100% of design pressure, with a permissible 10% overpressure / accumulation to relieving pressure.